MIL-PRF-15305 Coils, Electrical, Fixed And Variable, Radio Frequency General Specification ForThis specification covers the general requirements for radio frequency coils, fixed and variable, for use as simple inductive elements in radio frequency circuits. Procurement of coils of a specific design will require additional data in the form of complementary Service documents, giving detail electrical and mechanical requirements, tolerances, and applicable additions and exceptions to the general requirements and tests specified herein \(see 3.1\).

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MIL-PRF-15305F

3.6 Winding continuity (when applicable).

When coils are tested as specified in 4.6.3, all windings shall be

electrically continuous.

3.7 Operating torque (applicable only to variable coils). When coils are tested as specified in 4.6.4, the torque

required to rotate the tuning core shall be within the limits specified (see 3.1).

3.8 Electrical characteristics. The electrical characteristics shall be as specified (see 3.1 and 4.6.5).

3.8.1 Inductance. When coils are tested as specified in 4.6.5.1, the inductance shall be as specified (see 3.1).

3.8.2 Q of coils. When coils are tested as specified in 4.6.5.2, the Q shall be as specified (see 3.1).

3.8.3 Self-resonant frequency. When coils are tested as specified in 4.6.5.3, the self-resonant frequency shall be

not less than the minimum value specified (see 3.1).

When coils are tested as specified in 4.6.5.4 or 4.6.5.4.1, the percent

3.8.4 Percent coupling (when specified).

coupling shall be as specified (see 3.1).

3.8.5 Incremental current inductance change (when specified). When coils are tested as specified in 4.6.5.5, the

inductance value shall represent a change of 5 percent or less of the inductance measures with zero direct current (dc)

(see 3.1).

3.8.6 Effective parallel resistance (when specified). When coils are tested as specified in 4.6.5.6 or 4.6.5.6.1, the

effective parallel resistance shall be as specified (see 3.1).

DC resistance. When coils are tested as specified in 4.6.5.7, the dc resistance shall be as specified (see

3.8.7

3.1).

3.9 Temperature rise (applicable to cylindrical insulated coils and when specified). When coils are tested as

specified in 4.6.6 or 4.6.6.1, the temperature rise of any winding above the specified maximum ambient temperature

(see 3.1) shall not exceed the value specified (see 3.1) and there shall be no evidence of physical damage.

3.10 Overload. When coils are tested as specified in 4.6.7, there shall be no evidence of cracked cases, nor

loosening of the terminals.

3.11 Resistance to soldering heat. When coils are tested as specified in 4.6.8, there shall be no evidence of

mechanical damage, loosening of the terminals, or solder reflow as evidence by solder flowing from the body. Pretest

and posttest X-ray inspection at 10X shall be required.

3.12 Terminal strength. When coils are tested as specified in 4.6.9, there shall be no winding discontinuity, no

loosening or rupturing of the terminals, nor other mechanical damage.

3.13 Life. When coils are tested as specified in 4.6.10, there shall be no evidence of mechanical damage. The

changes in electrical characteristics between the initial measurements and 250 +48, -0 hours shall not exceed the

initial limits specified for phenolic and iron core coils and the electrical characteristics from the 250 +48, -0 hours up to

and including 2,000 hours shall not exceed the degradation limits specified (see 3.1). The change in electrical

characteristics for ferrite core coils between the initial measurements up to and including 2,000 hours shall not exceed

the degradation limits specified (see 3.1 and 6.7).

3.14 Low temperature storage. When coils are tested as specified in 4.6.11, there shall be no impairment of

protective coating, no loosening of the windings or terminals, nor any other evidence of mechanical damage.

3.15 Vibration. When coils are tested as specified in 4.6.12.1 or 4.6.12.2, there shall be no winding discontinuity

(see 3.6), nor evidence of physical or mechanical damage.

3.16 Shock (specified pulse). When coils are tested as specified in 4.6.13, there shall be no winding discontinuity

(see 3.6), nor evidence of physical or mechanical damage.

3.17 Moisture resistance (grades 1 and 2 only). When coils are tested as specified in 4.6.14, the electrical

characteristics shall be as specified in 3.8, and there shall be no evidence of corrosion affecting the mechanical or

electrical operation.

3.18 Fungus. All external materials shall be nonnutrient to fungus growth or shall be suitably treated to retard

fungus growth. The manufacturer shall verify by certification that all external materials are fungus resistant or shall test

the coils as specified in 4.6.15. There shall be no evidence of fungus growth on the external surfaces.